Lightly coat a cookie sheet with cooking spray.
Mix flour and baking soda in a small bowl; set aside.
With a spoon, mix butter, peanut butter and brown sugar in a medium bowl until smooth.
Add egg and vanilla; beat until smooth.
Add flour mixture and stir until combined.
Cover dough and refrigerate for 20-30 minutes.
Preheat oven to 375 degrees Fahrenheit.
Roll dough into 1-inch balls and bake for 8-10 minutes.
Remove from oven and allow to cool for 3 minutes.
Press two malted milk ball halves into each cookie, creating the body of the spider.
Allow cookies to cool completely.
Transfer melted chocolate chips into a ziplock bag.
Cut a small corner offto pipe 8 legs on each spider.
Using the white decorating gel, add two eyes to each spider.
Finally, using a toothpick, dab a small amount of melted chocolate in the middle of each white eye.